In many locations, water supplies are chemically and biologically polluted. Biologically contaminated water causes public health problems for not only people but also for livestock. Metropolitan areas have been reported to have problems with pathogens, unpleasant odors and undesirable tastes. Rural areas, too, are dealing with increasing contamination. Water supplies must be treated for a wide variety of microorganisms, including but not limited to, coliform bacteria such as E. coli, Klebsiella, Enterococcus faecalis, Campylobacter, and Salmonella, as well as protozoa such as Giardia lamblia. 
Chemical means of purifying drinking and/or industrial water, such as chlorine and hydrogen peroxide, therefore continue to be used on a wide scale. It is known that this method in particular does not provide water that can be consumed immediately: where necessary, such water must first be boiled before consumption.
Chlorinated water, for example, can cause problems ranging from nausea to more serious digestive problems in people with allergic reactions, in convalescents weakened by illness or in small children. Normally, therefore, the only water that can be consumed without any concerns about health risks is water drawn from certificated mineral springs and sold in suitable packaging. In countries and regions of the world with a serious drinking water shortage, water is therefore becoming an increasingly expensive commodity.
The overfertilisation of the soil in intensive farming and the penetration of such fertilisers into the groundwater further contribute to the scarcity of drinking and/or industrial water.
No devices and methods based on introducing an electric current into liquids, especially water, have yet been developed in accordance with the state of the art that enable water or other liquids contaminated by bacteria and/or viruses to be adequately purified.
A method and device is known from DE 2455205 for electrically purifying and sterilising liquids. In addition to water supplies, for example, for soldiers in the field, for geologists in remote areas and for other fields of application, this invention also produces water for medical/biological purposes. The invention has flowing current that is pulsating, with the duration of the current impulse and the voltage selected in such a way that electric discharges arise between the electrodes.
DE 100 14 289 A1 suggests a method based on electric currents and fields for carrying out disinfection to medical quality standards and for controlling biological processes in industrial production processes and products. In this invention a direct or alternating current, each of appropriate voltage, current and frequency, is [conducted] momentarily, at intervals or continuously via electrodes or by inductive or capacitive coupling into a substance and emitted. The said substance can be enriched with electrolytes and is in a conductive aggregate phase. The purpose of the invention is to rid the substance of all or some undesired spores, viruses, bacteria and other biologically active microorganisms as well as harmful parasites and microbes and their alternate hosts and/or their forms of development, in such a way that these are killed, rendered incapable of propagation or development or paralysed for short or long periods.
An electrostatic water sterilising device is known from EP 0647 594 A2, consisting of a flanged cylinder housing and an elongated electrode positioned in the centre of the housing, with a generator for electrostatic low voltage positioned outside the housing and a water inlet and a water outlet fitted next to two pieces of insulation at both ends of the housing. The entire inner surface of the whole of the housing is lined with a highly conductive material at a negative electric potential, so that it can act as a negative electrode. A low voltage electrostatic field is built up between the positive and negative electrode inside the housing after the generator is switched on.
A similar device is named in U.S. Pat. No. 3,766,050. This is a device for purifying liquids or solutions by means of electrical fields. The device consists of a vessel containing the liquid to be treated, whereby the walls of the vessel are made of dielectric material and electrodes positioned inside and outside in parallel arrangement and strength, which can be variable, produce electric fields used to purify the liquids.
Because water cannot yet be purified adequately electrically and because of the need to avoid using chemical means, as mentioned above, it is imperative to guarantee the very basis of all life—namely the adequate supply of drinking and/or industrial water—in extreme situations as well, e.g. in the supply of water from well systems in areas of low rainfall, where the soil is bacterially contaminated.